Fluorescent ribbons are generally employed to allow the coding of documents which can subsequently be read electronically (optically) in order to allow machine sorting of the documents.
The preparation of the ribbon with transferrable fluorescent material is accomplished by depositing a layer of fluorescent material and waxes on the surface of a thin film of plastic. Thin plastic film materials most often used as ribbon carriers are polyethylene or Mylar.
The waxy fluorescent material transfer to the printing surface is very thin and transparent to visual observation. This transparency of the imprinted fluorescent material on paper becomes a problem where the imprintation is over a darker colored portion of paper.
Daylight fluorescent materials can be viewed when excited by sunlight. Daylight fluorescent materials are transparent or translucent in nature and therefore applied over white primer inorder to obtain the maximum daylight fluorescent effect. The addition of the white opaque pigment in the formulation does not serve to enhance the fluorescence but rather reduce it to a tint and possibly may therefore reduce light fastness.
When a fluorescent material is deposited upon the surface of white paper the whiteness of the paper serves as a light reflector. The incident light passes through the pigments and penetrates the paper base to a slight degree depending upon the whiteness of the paper. Most of the incident light reflects off the paper and back through the fluorescent material imprinted on the paper. The reflected light will contain both incident and fluorescent light.
If the fluorescent material is deposited on the surface of a dark colored paper, part of the incident light will be absorbed by the paper. The amount of light available for reflection back through the fluorescent material is reduced proportional to the amount of light absorbed by the paper. This reduction in light reflection by the paper will lower the amount of energy available to produce emission from the fluorescent material.